A large amount of research work has been carried out for the purpose of providing elastomeric polymers for various aerospace seal and sealant applications. For a polymer to fulfill completely the rigid requirements of such applications, it must be thermooxidatively and hydrolytically stable while also being capable of retaining its elastomeric properties at sub-zero temperatures. In the past it has been possible to synthesize polymers possessing two of these properties which are outstanding while one of the properties is less satisfactory than desired. Thus, in U.S. Pat. Nos. 3,846,376 and 3,994,861 polymers are disclosed by me that possess a broad use temperature range. However, the polymers are often hydrolytically unstable when exposed to humid conditions at elevated temperatures for extended periods of time. In my copending U.S. application Ser. No. 710,088, filed on July 30, 1976, and now issued as U.S. Pat. No. 4,064,109, polymers are disclosed that advance the art in meeting all three of the aforementioned requirements. Thus, the polymers are thermally and hydrolytically stable and have a fairly low glass transition temperature (Tg). Since the Tg of a polymer is an indication of the temperature at which it retains its viscoelastic properties, there is still a need for thermally and hydrolytically stable polymers having even lower glass transition temperatures.
It is a principal object of this invention, therefore, to provide compounds that can be used as monomers in synthesizing thermooxidatively and hydrolytically stable polymers having improved low temperature viscoelastic properties.
Another object of the invention is to provide a process for preparing hybrid perfluoroalkylene ether thioimidate ester monomers.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.